Nearly two-thirds of secondary school leaders are prepared to take national industrial action to protect their pensions for the first time, a survey has revealed.

The poll by the Association of School and College Leaders (ASCL) - which shows that 63 per cent of respondents would take action to preserve their final salary schemes - comes less than a week before the publication of the Hutton review of public sector pensions.

Lord Hutton, the author of the Government-commissioned review, has already said he considers final salary schemes “unfair”.

The fighting talk from ASCL, whose 15,000 members have never taken collective industrial action, indicates the fury the Government could unleash if teachers are forced to swap to a so-called “career average” pension scheme.

Forty-three per cent of the 2,700 survey respondents who were prepared to take some form of industrial action said they would strike.

Currently, a secondary head earning the typical salary of pound;86,000 a year is eligible for a maximum annual pension of pound;43,000. Unions fear that under a crude average-salary scheme, that could fall as low as pound;31,000 a year.

The results follow a recent poll by heads’ union the NAHT which found that 64 per cent of its largely primary-based members would also be prepared to take action.

The Association of Teachers and Lecturers, which has not been involved in national action since the 1970s, has announced that it is preparing a formal ballot on industrial action.

One 50-year-old headteacher answering the ASCL survey said: “I am exhausted on a daily basis. I feel that I have done enough. I want to have what I believed I was entitled to and I would be angry to be let down at this last moment.

“My well-being is stretched to the limit daily as it is, my only solace is that I will be able to retire and live a decent life. It is grossly unfair to even worry me in this way.”

Another commented: “In my many years of teaching I have never considered taking action but I feel very strongly about this issue and have no plan B for when I retire.”

A third said it was “an outrage” that the Government was considering reforming their pensions mid-contract.

Brian Lightman, general secretary of ASCL, said: “It’s clear that our members are extremely angry at potential threats to the scheme. It’s unusual for this strength of feeling to be so evident among ASCL members. They feel it’s an integral part of the overall package of the job they do.”

He said many members felt the Government had gone far enough with reforms in 2007, which raised the retirement age for new entrants and increased employee contributions. He added: “Striking would be an absolute last resort, but the Government needs to hear the message that feelings are running very, very high and headteachers are prepared to fight for something enormously important.”

Professor Howard Stevenson, school industrial relations expert at Lincoln University, said it was “almost unprecedented” for heads’ unions to take traditional forms of industrial action.

“It is clear that the threat to pensions is emerging as one of the central issues around which public sector workers are likely to mobilise on a massive scale,” he said. “When headteacher unions respond in this way the government needs to understand the scale of the fight it is taking on.”

Chancellor George Osborne hopes to raise the average teacher contributions to their pensions from 6.4 per cent to between 9.5 and 9.8 per cent over the next four years.

Despite the concerns over final salary schemes, the ASCL poll indicated some acceptance over plans to increase contributions.

Almost 88 per cent of respondents said they would be prepared to pay more if it meant preserving the final salary scheme, with 70 per cent saying they would be prepared to pay an increase of between two and three per cent.

A spokesman for the Department for Education said: “Ministers are committed to working with unions and involving them in discussions over pension reforms. But the fact is, people are living longer and public sector workers are going to have to pay more for their pensions.”

• Original headline: Secondary leaders pledge industrial action on pensions